Corrosion behaviors of W-doped laser-cladded high-entropy alloy of AlCoCrFeNi in a simulated sulfur-containing seawater environment

The localized corrosion in a simulated seawater environment is related to sulfide, and few studies have investigated the corrosion behaviors of laser-cladded AlCoCrFeNi high-entropy alloy (HEA) systems in a simulated sulfur-containing seawater environment. Corrosion behaviors of HEA/Wx (x = 0, 5, and 15 wt%) coatings have been worked out by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, X-ray photoelectron spectroscopy (XPS) analysis, and immersion corrosion tests. W-doped HEA coatings can change the ratio of A2 to B2 phases and affect the corrosion resistance. The potentiodynamic polarization and EIS results reveal that a small quantity of W-doped (5 wt%) HEA coatings form a denser passivation film that is particularly resistant to localized corrosion. By analyzing the corrosion behaviors of the HEA/Wx coatings, it was determined that a small amount of W-doped (5 wt%) HEA coatings had better localized and improved corrosion resistance. However, excessively W-doped (15 wt%) HEA coatings have reduced corrosion resistance. The Mott-Schottky analysis revealed that the HEA/Wx coatings (x = 0, 5, and 15 wt%) have the property of P–N-type semiconductors. XPS analysis was used to analyze the film composition. The results demonstrated that the passivation film combined Cr2O3, Al2O3, Fe2O3, and WO3. Based on the immersion corrosion test, localized corrosion types were mainly intergranular and crevice.